This is the second class action suit brought against Subaru by a California-based law firm, McCune Wright Arevalo LLP. The parties last year settled a suit alleging excessive oil consumption by multiple Subaru models made between 2011 and 2015.

The latest suit, filed Thursday in federal court, Camden, "is the result of an extensive investigation by our firm during the past year," said attorney Matthew Schelkopf at the law firm's East Coast offices in Berwyn, Pennsylvania.

The WRX and WRX STI models, marketed as high-performance, "sporty" vehicles, sold almost 25,500 units in 2014, an annual increase of about 42 percent. The brand sold more than 16,000 units in 2013, also marking a sharp jump from year-before levels.

The suit, which contends Subaru failed to disclose the problem to consumers, focuses on an engine component known as a rotating assembly.

Among other demands, it wants Subaru to notify consumers of the alleged defect and to reimburse drivers for repairs and other expenses.

It says the potential cost to Subaru, a Japanese-based automaker and owner of the Cherry Hill firm, could be more than $5 million.

The suit was filed in the name of Vincent Salcedo, a California man who says his 2013 WRX developed a "knocking" sound, then broke down on a highway in July of this year.

Salcedo faced a repair bill of about $5,700 due to damage caused by metal shavings from a failed connecting rod. Subaru offered to pay $2,000 of that amount as a goodwill gesture, the lawsuit adds.

The lawsuit says Salcedo would not have purchased his car, or would have paid less, had he known of the alleged engine defect.

It agreed to extended warranty protections for Forester, Impreza, Crosstrek, Legacy and Outback models made from 2011 through 2015. More than 665,000 people owned or leased vehicles in those categories, according to the suit.

The settlement also provided free oil-consumption testing, reimbursement for eligible expenses and, when necessary, a new engine "and other countermeasures" in some vehicles with oil-burning issues.